1.0.23.57: rewrite bug 217

 * Case A is a non-issue. SBCL interprets "unpredictable but harmless"
   to mean "anything, but heap will no be corrupted, data lost, etc"
   -- that is, an error may or may not be signalled, but it the lisp
   session will remain sane and operable.

 * Case B is negated by the portability argument: since specifying both
   is unspecified, we should not build useful-seeming extensions on top
   of it, as it will only create portability problems for users.

 * Case C remains partially valid, except for the runtime WARNINGs.
   Integrated into the new text.

BUGS

@@ -606,21 +606,14 @@ WORKAROUND:
  can erroneously return T.
 
 215: ":TEST-NOT handling by functions"
- a. FIND and POSITION currently signal errors when given non-NIL for
- both their :TEST and (deprecated) :TEST-NOT arguments, but by
- ANSI 17.2 "the consequences are unspecified", which by ANSI 1.4.2
- means that the effect is "unpredictable but harmless". It's not
- clear what that actually means; it may preclude conforming
- implementations from signalling errors.
- b. COUNT, REMOVE and the like give priority to a :TEST-NOT argument
- when conflict occurs. As a quality of implementation issue, it
- might be preferable to treat :TEST and :TEST-NOT as being in some
- sense the same &KEY, and effectively take the first test function in
- the argument list.
- c. Again, a quality of implementation issue: it would be good to issue a
- STYLE-WARNING at compile-time for calls with :TEST-NOT, and a
- WARNING for calls with both :TEST and :TEST-NOT; possibly this
- latter should be WARNed about at execute-time too.
+
+ We should verify that our handling of :TEST-NOT and :TEST is consistent
+ for all functions that accept them: that is, signal an error if both
+ are specified.
+
+ Similarly, a compile-time full warning for calls with both would be good.
+
+ We might also consider a compile-time style warning for :TEST-NOT.
 
 216: "debugger confused by frames with invalid number of arguments"
  In sbcl-0.7.8.51, executing e.g. (VECTOR-PUSH-EXTEND T), BACKTRACE, Q

version.lisp-expr

@@ -17,4 +17,4 @@
 ;;; checkins which aren't released. (And occasionally for internal
 ;;; versions, especially for internal versions off the main CVS
 ;;; branch, it gets hairier, e.g. "0.pre7.14.flaky4.13".)
-"1.0.23.56"
+"1.0.23.57"